JPH05101566A - Magnetic disk device - Google Patents

Abstract

(57) [Summary] [Purpose] Without reducing the storage capacity of data,
An object of the present invention is to provide a magnetic disk device capable of positioning a head on a target track with high speed and high accuracy. [Structure] It has a disk structure in which arrangement information 19 of servo information and control function information 20 of servo information are added after the DC erase unit 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device having a head control system capable of high-speed and high-precision positioning.

[0002]

2. Description of the Related Art Conventionally, in a magnetic disk device, servo information is magnetically formed on one surface of a magnetic disk incorporated in the device to position a servo head on a target track, and one magnetic disk surface is used as a data surface. A servo surface servo system that records and reproduces information using a data head is widely adopted. However, in this method, due to a change in the operating environment of the magnetic disk device, particularly a temperature rise, a positional deviation between the servo track on the servo surface and the data track on the data surface, so-called thermal off-track, is likely to occur, and data recording / reproduction is unstable Therefore, there is a problem that the track density cannot be increased.

Therefore, recently, a data surface servo system in which the entire surface of a magnetic disk incorporated in a magnetic disk device is used as a data surface and servo information is discretely formed on the data surface to position the magnetic head on a target track. Is being adopted.

However, in this data surface servo system,
Since the servo information serving as the speed information and the position information can be obtained only in the servo sectors discretely formed on the data surface, it is difficult to detect the servo information when the actuator equipped with the magnetic head is moved at high speed, and There is a problem that it is difficult to position the head on the target track at high speed and with high accuracy. In order to solve this problem, the amount of servo information should be increased, but if this is simply done, the ratio of servo information to the magnetic disk increases, that is, the format efficiency decreases, and as a result, However, there is a problem in that the storage capacity of the device is significantly reduced.

Therefore, various magnetic head control methods have been proposed which can position the magnetic head on a target track at high speed and with high accuracy.

For example, Japanese Laid-Open Patent Publication No. 51-131607 proposes a method in which, in addition to servo information for precise positioning, a track number is coded and recorded on a magnetic disk to perform rough positioning of a magnetic head. Has been done. However, in this method, the track number may not be readable when the magnetic head is attempted to move at a higher speed or when there is a defect in the magnetic disk. Positioning is not always possible. In addition, since the track number is coded and recorded on the magnetic disk, when an attempt is made to increase the capacity of the magnetic disk device by increasing the number of tracks, since the amount of information coded the track number increases, The ratio of servo information to the disk increases, that is, the format efficiency decreases, and as a result, the data storage capacity decreases.

Therefore, in order to solve the above problems,
In Japanese Patent Laid-Open No. 60-193176, the same number of sectors provided at equal angular intervals on each data surface of a magnetic disk having recording areas on opposite surfaces have a phase of 1 in the circumferential direction.
/ 2 sectors are arranged at different positions, the servo sectors are alternately detected from the sectors of each data surface arranged in this way in accordance with the rotation of the magnetic disk, and the servo information of each data surface is read out, so that the magnetic head is set as a target track. Positioning methods have been proposed.

A conventional magnetic disk device disclosed in Japanese Patent Laid-Open No. 60-193176 will be described below with reference to FIGS. 4, 5 and 6.

FIG. 4 schematically shows the recording pattern of the magnetic disk. In the figure, 6 is a servo sector, 7 is a data sector, and 6 and 7 form sector 1. Further, each surface of the magnetic disk, that is, each track on the upper surface and the lower surface is divided into sectors 1 provided at equal angular intervals, and the relative positional relationship between the sectors on each surface is such that the phase in the circumferential direction is 1/2. The sectors are arranged differently.
As shown in FIG. 5, each sector is a servo sector magnetically embedded by four parts, namely, a DC erase section 2, an AGC (auto gain control) section 3, a zone section 4, and a speed and position information section 5. 6 and a data sector 7 for recording / reproducing data. The servo sector 6 is prohibited from being recorded by the magnetic head.

Next, the process of detecting servo information from a magnetic disk having servo information embedded in each surface in this way will be described with reference to FIG.

First, a signal reproduced by the magnetic head 25 from the magnetic disk 26 having a track to be accessed for recording and reproducing data by the magnetic head changeover switch 8 is amplified by a reproducing amplifier 27 and then a servo signal. The DC erase unit 2 which is input to the detection circuit and located at the head of each sector is detected by the DC erase detection circuit 9. Then, in synchronization with this DC erase, the gate generation circuit 10 generates a gate signal having a predetermined time width at each position of the AGC portion, zone portion, speed and position information portion, and each signal is taken out. Further, the peak values of the speed signals X, Y, Z and the position signals A, B formed in the speed and position information section are sequentially held by the peak hold circuit 11 during the period when the gate is open, and the A / D converter is used. It is taken into the CPU 14 through the I / O port 12 and the I / O port 13, and a velocity signal and a position signal are created by calculation. When each signal is taken out, a signal having the time width of the data sector is generated by the gate generation circuit. This section is a section in which data can be recorded and reproduced, and recording by the magnetic head is prohibited in other sections. Immediately after the above signals are taken out from this data surface, the changeover switch 8 of the magnetic head is switched by the CPU 14, the signal read from the other surface is taken in to the servo signal detection circuit, and the AGC is performed in the same process as above. Section, zone section,
Each signal of the speed and position information section is taken out. Further, when each signal is taken in, the changeover switch of the magnetic head is changed over. At this timing, the width of the data sector generated in the sector of the surface on which the track to be accessed for recording / reproducing data exists is determined. As soon as the CPU detects the end of the gate signal it has, it switches. By repeating the above process according to the rotation of the magnetic disk, the servo information is alternately taken out from each data surface, and the CPU 14 calculates the velocity signal and the position signal, and the I / O port 15 and the D / O port 15
VCM (Voice coil motor Voic via A converter 16)
(e Coil Moter) driver 17 and drives an actuator 18 having a magnetic head to position the magnetic head on a target track.

With such a configuration, not only the servo information obtained from only the surface on which the track to be accessed for recording / reproducing data is present, but also the servo information on the surface opposite to the servo information is the data of the track to be accessed. By being obtained at the position within the sector, it is possible to exhibit more faithful followability with respect to the track shake in the data sector.

Further, by alternately sampling from the sectors of each data surface whose phases in the circumferential direction are different from each other by 1/2 sector to obtain servo information, the sampling frequency becomes twice as high as in the case of obtaining servo information from one surface. Therefore, the servo response band can be doubled, and as a result, the gain of the servo system at the fundamental frequency of track shake can be improved four times.

Furthermore, since the cycle of detected sectors is halved, it is equivalent to doubling the number of sectors when servo information is obtained from only one side, and the maximum speed during seek is doubled. It is possible to raise.

[0015]

However, as in the above-mentioned conventional structure, the same number of sectors are provided in the circumferential direction at the same number of sectors on each data surface of the magnetic disk having the recording areas on the opposite surfaces. The phases are arranged at positions different from each other by ½ sector, servo sectors are alternately detected from the sectors on each data surface arranged in this manner according to the rotation of the magnetic disk, and the servo information on each data surface is read to position the magnetic head. In the servo system used, two magnetic heads are used for speed control of an actuator having a magnetic head, and one magnetic head is used for position control.

Therefore, if the relative positions of the two magnetic heads are displaced due to thermal off-track or impact due to changes in the environment, for example, high speed will occur when switching from the first magnetic head to the second magnetic head. Judgment is made, and when switching from the second magnetic head to the first magnetic head, it is judged as a low speed, so that speed detection becomes uncertain, and high-accuracy speed control cannot be performed, so that stability as a control system is achieved. There is a case where it does not get the nature and goes out of control.

Further, as described above, since the speed detection varies during the speed control, the plunge speed also varies when the speed control is switched to the position control. Therefore, the position of the magnetic head causes overshoot or undershoot with respect to the position of the target track, which requires a long time for settling, and the predetermined access time as a magnetic disk drive cannot be satisfied.

Further, since two magnetic heads are used for speed control of the actuator having the magnetic head, one of the magnetic heads constituting the magnetic disk drive device is the head. When a crash is caused or the output is lowered, a normal magnetic head cannot seek the target track, and reliability as a magnetic disk drive device cannot be obtained.

The present invention solves such a conventional problem, and speed control and position control of an actuator equipped with a magnetic head are performed without reducing the storage capacity of data, and the magnetic head is realized. An object of the present invention is to provide a large-capacity magnetic disk device that can be positioned on a target track at high speed and with high accuracy.

[0020]

In order to achieve the above-mentioned object, the present invention adds the arrangement information of servo information and the control function information of servo information after the DC erase section, and
A plurality of servo information is magnetically embedded between the C erase portions.

[0021]

According to the present invention, since a plurality of servo information can be arranged between the DC erase section and the DC erase section by the above-mentioned structure, the sampling frequency per magnetic disk surface can be increased. Further, it is possible to detect a plurality of servo information between DC erase parts with one DC erase part. Further, it is possible to classify a plurality of servo information between the DC erase parts by control function, that is, servo information for speed control or servo information for position control. Since the frequency and the sampling frequency at the time of position control can be increased and those frequencies can be arbitrarily set, the sampling frequency at the time of speed control can be set higher than the sampling frequency at the time of position control. Therefore, an accurate speed signal can be obtained even when an actuator having a magnetic head is driven at high speed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a recording pattern of a magnetic disk. In the drawing, 6 is a servo sector and 7 is a data sector. The servo sector 6 has a wide width in the circumferential direction of the magnetic disk. It is composed of two types, a narrow one 6a and a narrow one 6b. Further, the positional relationship of each sector is provided in the circumferential direction of the magnetic disk in the order of wide servo sector 6a, data sector 7, narrow servo sector 6b, and data sector 7.

FIG. 2 is a detailed view of the periphery of the servo sector portion shown in FIG. The servo sector 6a, which is wide in the circumferential direction of the magnetic disk, includes the DC erase section 2, the AGC section 3, the zone section 4, the servo information arrangement information 19, the servo information control function information 20, and the first servo information 21. It is configured. Further, the servo sector 6b having a narrow width in the circumferential direction of the magnetic disk is composed of the second servo information 22.
The zone portion 4 is an area in which zone information of the magnetic disk is recorded, and the servo information arrangement information 19 stores information regarding the number and arrangement position of a plurality of servo information formed between the DC erase portions. The control function information 20 of the servo information is a certain area, and a plurality of servo information formed between the DC erase portions is recorded with information indicating whether it is used for speed control or position control. The certain servo information 21 and the second servo information 22 are areas in which servo information used during speed control or position control is recorded. Note that recording by the magnetic head is prohibited in these two servo sectors. In addition, in the example of FIG. 2, the first servo information 21 is provided with servo information 21a used during speed control and servo information 21b used during position control.
2 shows a case where the servo information 21a used during speed control is provided. Servo information 2 used during speed control
1a is composed of a speed signal Z composed of a two-phase dibit pattern having a cycle of 4 tracks, and speed signals X and Y composed of two dibit patterns having a cycle of 16 tracks and having a deviation of 4 tracks. Therefore, the position of the head with respect to the magnetic disk can be detected with high accuracy even when the head moves at high speed. Further, the servo information 21b used in the position control is composed of two magnetization reversal parts, and the two magnetization reversal parts are equal to the width of the data track, and each of the two sides of the data track is 1 / width of the data track. It is configured to be displaced by 2 and also configured to be displaced in the longitudinal direction of the data tracks so that no overlap occurs. Then, the position of the head is detected based on the reproduction signal amplitudes of the two magnetization reversal portions.

Next, the process of detecting the servo information from the magnetic disk in which the servo information is embedded and formed on each surface as described above will be described with reference to FIG. In addition, in FIG.
The same numbers as in FIG. 6 indicate the same functions.

In FIG. 3, a signal reproduced from the magnetic disk 26 by the magnetic head 25 is a reproduction amplifier 27.
Then, the DC erase detection circuit 9 detects the DC erase section 2 located at the head of each sector by not generating a signal for a certain period of time. Then, in synchronization with this DC erase, the gate generation circuit 10 generates various gate signals. The gate signal generated at the position of the zone portion 4 is for judging the zone of the magnetic disk, that is, the inner and outer peripheral areas and the data area. The gate signal generated at the position of the arrangement information 19 of the servo information is D
This is for the arrangement information discriminating circuit 23 to judge the number and arrangement position of a plurality of servo information formed between the C erase portions. Further, the gate signal generated at the position of the control function information 20 of the servo information indicates whether a plurality of servo information formed between the DC erase portions is used for speed control or position control. This is for making a judgment by the control function judging circuit 24. Figure 2
In the above example, as described above, in the arrangement information 19 of the servo information,
There is information that two pieces of servo information are provided between the DC erase parts, and the control function information 20 of the servo information is included.
In the case where there is information that the first servo information is the servo information used during the speed control and the position control, and the second servo information is the servo information used during the speed control. A gate signal for detecting two servo information existing between the DC erase portions by reading the information recorded in the arrangement information 19 of the servo information and the control function information 20 of the servo information and judging the information. To occur. Then, the gate opens the speed signals X, Y, Z and the position signals A, B formed in the first servo information 21 and the speed signals X, Y, Z formed in the second servo information 22. During the period, the peak hold circuit 11 sequentially holds the peak value, and the peak value is held by the CPU 14 through the A / D converter 12 and the I / O port 13, and the velocity signal and the position signal are created by calculation. When each signal is taken out, a signal having the time width of the data sector is generated by the gate generation circuit. This section is a section in which data can be recorded and reproduced, and recording by the magnetic head is prohibited in other sections. And like this,
Each servo information is fetched by the CPU 14, and the CPU 14 calculates the speed signal and the position signal. Furthermore, V via the I / O port 15 and D / A converter 16
It is input to the CM driver 17 to drive the actuator 18 having a magnetic head to position the magnetic head on a target track.

As described above, according to the magnetic disk device of the embodiment of the present invention, by adding the arrangement information of the servo information after the DC erase portion, the DC erase portion and the DC erase portion are added.
Since it is possible to arrange a plurality of servo information between the erase parts, the sampling frequency per one surface of the magnetic disk can be increased. Also, by adding the arrangement information of the servo information after the DC erase section,
Since it is possible to detect a plurality of servo information between DC erase parts with one DC erase part, before the second and subsequent servo information among the plurality of servo information between the DC erase parts, the DC information can be detected. Since it is not necessary to dispose the erase section and the AGC section, even if the number of servo information is increased, the data storage capacity is not reduced. Further, by adding the control function information of the servo information after the DC erase section, it becomes possible to classify the control functions of a plurality of servo information between the DC erase sections. Therefore, it is possible to increase the sampling frequency at the time of speed control and the sampling frequency at the time of position control per one surface of the magnetic disk, and to set those frequencies arbitrarily. That is, the sampling frequency during speed control can be set higher than the sampling frequency during position control. Therefore, even when the actuator having the magnetic head is driven at high speed, it is possible to obtain an accurate speed signal.

In this embodiment, the magnetic disk has been described, but it goes without saying that it can also be used for an optical disk or the like.

[0029]

As is apparent from the above embodiment, according to the present invention, a plurality of servo information is arranged between DC erase parts by adding servo information arrangement information and control function information after the DC erase part. Since it is possible to increase the sampling frequency per surface of the magnetic disk, it is possible to set those frequencies arbitrarily, and speed control is possible even with one magnetic head. Even if the relative positions of the magnetic heads that make up the drive are misaligned due to thermal offtrack due to changes in the environment, there is no variation in speed detection, and high-accuracy speed control is possible. The stability of the control system is obtained, and the speed can be controlled with one magnetic head. The variation in the inrush speed when switching to is reduced, and the position of the magnetic head does not overshoot or undershoot with respect to the target track position.Therefore, the settling time can be shortened. The access time as a drive is improved and a plurality of servo information can be detected by one DC erase section. Therefore, it is not necessary to provide the DC erase section and the AGC section for each servo information, and the entire magnetic disk is covered. The format efficiency per hit is improved, and a large-capacity magnetic disk device can be provided.

[Brief description of drawings]

FIG. 1 is a plan view showing an arrangement of data sectors and servo sectors of a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a servo sector portion of a magnetic disk drive device according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a control circuit of a magnetic head of a magnetic disk drive device according to an embodiment of the present invention.

FIG. 4 is a plan view showing an arrangement of data sectors and servo sectors of a conventional magnetic disk drive device.

FIG. 5 is an explanatory diagram of a servo sector section of a conventional magnetic disk drive device.

FIG. 6 is a block diagram showing a configuration of a control circuit of a magnetic head of a conventional magnetic disk drive device.

[Explanation of symbols]

 2 DC erase part 3 AGC part 4 Zone part 5 Velocity and position information part 6 Servo sector 6a Servo sector 6b with wide circumferential direction of magnetic disk 6b Servo sector with narrow width in circumferential direction of magnetic disk 11 Peak hold circuit 12 A / D Converter 13 I / O port 14 CPU 15 I / O port 16 D / A converter 17 VCM driver 18 Actuator 19 Servo information placement information 20 Servo information control function information 21 First servo information 21a Servo used during speed control Information 21b Servo information used during position control 22 Second servo information 23 Arrangement information discrimination circuit 24 Control function discrimination circuit 26 Magnetic disk

Claims (4)

[Claims] 1. A data surface servo type magnetic disk drive device in which servo information for positioning a magnetic head to a target track is magnetically embedded and formed on the same magnetic disk surface as a data recording surface, A magnetic disk device in which a plurality of servo information is formed between DC erase portions. 2. Arrangement information of the servo information is added after the DC erase portion, and the arrangement information of the servo information is used to determine the number and arrangement position of a plurality of servo information formed between the DC erase portions. 2. The magnetic disk drive according to claim 1, further comprising magnetic head control means for positioning the magnetic head on a target track according to the servo information. 3. A control function information of servo information is added after the DC erase portion, and a control function of servo information formed between the DC erase portions is judged by the control function information of the servo information. 2. The magnetic disk drive according to claim 1, further comprising magnetic head control means for positioning the magnetic head on a target track according to the servo information. 4. Arrangement information and control function information of the servo information is added after the DC erase section, and a plurality of servo information is formed between the DC erase sections by the arrangement information and control function information of the servo information. 2. The magnetic disk drive according to claim 1, further comprising magnetic head control means for determining the number, the arrangement position, and the control function, and positioning the magnetic head on a target track according to the servo information.